#!/bin/sh # # Script for automatic setup of an IPsec VPN server on Amazon Linux 2 # Works on any dedicated server or virtual private server (VPS) # # DO NOT RUN THIS SCRIPT ON YOUR PC OR MAC! # # The latest version of this script is available at: # https://github.com/hwdsl2/setup-ipsec-vpn # # Copyright (C) 2020-2021 Lin Song # # This work is licensed under the Creative Commons Attribution-ShareAlike 3.0 # Unported License: http://creativecommons.org/licenses/by-sa/3.0/ # # Attribution required: please include my name in any derivative and let me # know how you have improved it! # ===================================================== # Define your own values for these variables # - IPsec pre-shared key, VPN username and password # - All values MUST be placed inside 'single quotes' # - DO NOT use these special characters within values: \ " ' YOUR_IPSEC_PSK='' YOUR_USERNAME='' YOUR_PASSWORD='' # Important notes: https://git.io/vpnnotes # Setup VPN clients: https://git.io/vpnclients # IKEv2 guide: https://git.io/ikev2 # ===================================================== export PATH="/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin" SYS_DT=$(date +%F-%T | tr ':' '_') exiterr() { echo "Error: $1" >&2; exit 1; } exiterr2() { exiterr "'yum install' failed."; } conf_bk() { /bin/cp -f "$1" "$1.old-$SYS_DT" 2>/dev/null; } bigecho() { echo; echo "## $1"; echo; } check_ip() { IP_REGEX='^(([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])\.){3}([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])$' printf '%s' "$1" | tr -d '\n' | grep -Eq "$IP_REGEX" } vpnsetup() { os_arch=$(uname -m | tr -dc 'A-Za-z0-9_-') if ! grep -qs "Amazon Linux release 2" /etc/system-release; then echo "Error: This script only supports Amazon Linux 2." >&2 echo "For Ubuntu/Debian, use https://git.io/vpnsetup" >&2 echo "For CentOS/RHEL, use https://git.io/vpnsetup-centos" >&2 exit 1 fi if [ "$(id -u)" != 0 ]; then exiterr "Script must be run as root. Try 'sudo sh $0'" fi def_iface=$(route 2>/dev/null | grep -m 1 '^default' | grep -o '[^ ]*$') [ -z "$def_iface" ] && def_iface=$(ip -4 route list 0/0 2>/dev/null | grep -m 1 -Po '(?<=dev )(\S+)') def_state=$(cat "/sys/class/net/$def_iface/operstate" 2>/dev/null) if [ -n "$def_state" ] && [ "$def_state" != "down" ]; then case $def_iface in wl*) exiterr "Wireless interface '$def_iface' detected. DO NOT run this script on your PC or Mac!" ;; esac NET_IFACE="$def_iface" else eth0_state=$(cat "/sys/class/net/eth0/operstate" 2>/dev/null) if [ -z "$eth0_state" ] || [ "$eth0_state" = "down" ]; then exiterr "Could not detect the default network interface." fi NET_IFACE=eth0 fi [ -n "$YOUR_IPSEC_PSK" ] && VPN_IPSEC_PSK="$YOUR_IPSEC_PSK" [ -n "$YOUR_USERNAME" ] && VPN_USER="$YOUR_USERNAME" [ -n "$YOUR_PASSWORD" ] && VPN_PASSWORD="$YOUR_PASSWORD" if [ -z "$VPN_IPSEC_PSK" ] && [ -z "$VPN_USER" ] && [ -z "$VPN_PASSWORD" ]; then bigecho "VPN credentials not set by user. Generating random PSK and password..." VPN_IPSEC_PSK=$(LC_CTYPE=C tr -dc 'A-HJ-NPR-Za-km-z2-9' < /dev/urandom | head -c 20) VPN_USER=vpnuser VPN_PASSWORD=$(LC_CTYPE=C tr -dc 'A-HJ-NPR-Za-km-z2-9' < /dev/urandom | head -c 16) fi if [ -z "$VPN_IPSEC_PSK" ] || [ -z "$VPN_USER" ] || [ -z "$VPN_PASSWORD" ]; then exiterr "All VPN credentials must be specified. Edit the script and re-enter them." fi if printf '%s' "$VPN_IPSEC_PSK $VPN_USER $VPN_PASSWORD" | LC_ALL=C grep -q '[^ -~]\+'; then exiterr "VPN credentials must not contain non-ASCII characters." fi case "$VPN_IPSEC_PSK $VPN_USER $VPN_PASSWORD" in *[\\\"\']*) exiterr "VPN credentials must not contain these special characters: \\ \" '" ;; esac if { [ -n "$VPN_DNS_SRV1" ] && ! check_ip "$VPN_DNS_SRV1"; } \ || { [ -n "$VPN_DNS_SRV2" ] && ! check_ip "$VPN_DNS_SRV2"; } then exiterr "The DNS server specified is invalid." fi bigecho "VPN setup in progress... Please be patient." # Create and change to working dir mkdir -p /opt/src cd /opt/src || exit 1 bigecho "Installing packages required for setup..." yum -y install wget bind-utils openssl tar \ iptables iproute gawk grep sed net-tools || exiterr2 bigecho "Trying to auto discover IP of this server..." cat <<'EOF' In case the script hangs here for more than a few minutes, press Ctrl-C to abort. Then edit it and manually enter IP. EOF # In case auto IP discovery fails, enter server's public IP here. PUBLIC_IP=${VPN_PUBLIC_IP:-''} [ -z "$PUBLIC_IP" ] && PUBLIC_IP=$(dig @resolver1.opendns.com -t A -4 myip.opendns.com +short) check_ip "$PUBLIC_IP" || PUBLIC_IP=$(wget -t 3 -T 15 -qO- http://ipv4.icanhazip.com) check_ip "$PUBLIC_IP" || exiterr "Cannot detect this server's public IP. Edit the script and manually enter it." bigecho "Adding the EPEL repository..." amazon-linux-extras install epel -y || exiterr2 bigecho "Installing packages required for the VPN..." REPO1='--enablerepo=epel' yum -y install nss-devel nspr-devel pkgconfig pam-devel \ libcap-ng-devel libselinux-devel curl-devel nss-tools \ flex bison gcc make ppp \ systemd-devel iptables-services \ libevent-devel fipscheck-devel || exiterr2 yum "$REPO1" -y install xl2tpd || exiterr2 bigecho "Installing Fail2Ban to protect SSH..." yum "$REPO1" -y install fail2ban || exiterr2 bigecho "Compiling and installing Libreswan..." SWAN_VER=4.2 swan_file="libreswan-$SWAN_VER.tar.gz" swan_url1="https://github.com/libreswan/libreswan/archive/v$SWAN_VER.tar.gz" swan_url2="https://download.libreswan.org/$swan_file" if ! { wget -t 3 -T 30 -nv -O "$swan_file" "$swan_url1" || wget -t 3 -T 30 -nv -O "$swan_file" "$swan_url2"; }; then exit 1 fi /bin/rm -rf "/opt/src/libreswan-$SWAN_VER" tar xzf "$swan_file" && /bin/rm -f "$swan_file" cd "libreswan-$SWAN_VER" || exit 1 cat > Makefile.inc.local <<'EOF' WERROR_CFLAGS=-w USE_DNSSEC=false USE_DH2=true USE_NSS_KDF=false FINALNSSDIR=/etc/ipsec.d EOF if ! grep -qs IFLA_XFRM_LINK /usr/include/linux/if_link.h; then echo "USE_XFRM_INTERFACE_IFLA_HEADER=true" >> Makefile.inc.local fi NPROCS=$(grep -c ^processor /proc/cpuinfo) [ -z "$NPROCS" ] && NPROCS=1 make "-j$((NPROCS+1))" -s base && make -s install-base cd /opt/src || exit 1 /bin/rm -rf "/opt/src/libreswan-$SWAN_VER" if ! /usr/local/sbin/ipsec --version 2>/dev/null | grep -qF "$SWAN_VER"; then exiterr "Libreswan $SWAN_VER failed to build." fi bigecho "Creating VPN configuration..." L2TP_NET=${VPN_L2TP_NET:-'192.168.42.0/24'} L2TP_LOCAL=${VPN_L2TP_LOCAL:-'192.168.42.1'} L2TP_POOL=${VPN_L2TP_POOL:-'192.168.42.10-192.168.42.250'} XAUTH_NET=${VPN_XAUTH_NET:-'192.168.43.0/24'} XAUTH_POOL=${VPN_XAUTH_POOL:-'192.168.43.10-192.168.43.250'} DNS_SRV1=${VPN_DNS_SRV1:-'8.8.8.8'} DNS_SRV2=${VPN_DNS_SRV2:-'8.8.4.4'} DNS_SRVS="\"$DNS_SRV1 $DNS_SRV2\"" [ -n "$VPN_DNS_SRV1" ] && [ -z "$VPN_DNS_SRV2" ] && DNS_SRVS="$DNS_SRV1" # Create IPsec config conf_bk "/etc/ipsec.conf" cat > /etc/ipsec.conf < /etc/ipsec.secrets < /etc/xl2tpd/xl2tpd.conf < /etc/ppp/options.xl2tpd <> /etc/ppp/options.xl2tpd < /etc/ppp/chap-secrets < /etc/ipsec.d/passwd <> /etc/sysctl.conf < "$F2B_FILE" <<'EOF' [ssh-iptables] enabled = true filter = sshd logpath = /var/log/secure action = iptables[name=SSH, port=ssh, protocol=tcp] EOF fi bigecho "Updating IPTables rules..." IPT_FILE=/etc/sysconfig/iptables ipt_flag=0 if ! grep -qs "hwdsl2 VPN script" "$IPT_FILE"; then ipt_flag=1 fi if [ "$ipt_flag" = "1" ]; then service fail2ban stop >/dev/null 2>&1 iptables-save > "$IPT_FILE.old-$SYS_DT" iptables -I INPUT 1 -p udp --dport 1701 -m policy --dir in --pol none -j DROP iptables -I INPUT 2 -m conntrack --ctstate INVALID -j DROP iptables -I INPUT 3 -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT iptables -I INPUT 4 -p udp -m multiport --dports 500,4500 -j ACCEPT iptables -I INPUT 5 -p udp --dport 1701 -m policy --dir in --pol ipsec -j ACCEPT iptables -I INPUT 6 -p udp --dport 1701 -j DROP iptables -I FORWARD 1 -m conntrack --ctstate INVALID -j DROP iptables -I FORWARD 2 -i "$NET_IFACE" -o ppp+ -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT iptables -I FORWARD 3 -i ppp+ -o "$NET_IFACE" -j ACCEPT iptables -I FORWARD 4 -i ppp+ -o ppp+ -s "$L2TP_NET" -d "$L2TP_NET" -j ACCEPT iptables -I FORWARD 5 -i "$NET_IFACE" -d "$XAUTH_NET" -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT iptables -I FORWARD 6 -s "$XAUTH_NET" -o "$NET_IFACE" -j ACCEPT # Uncomment to disallow traffic between VPN clients # iptables -I FORWARD 2 -i ppp+ -o ppp+ -s "$L2TP_NET" -d "$L2TP_NET" -j DROP # iptables -I FORWARD 3 -s "$XAUTH_NET" -d "$XAUTH_NET" -j DROP iptables -t nat -I POSTROUTING -s "$XAUTH_NET" -o "$NET_IFACE" -m policy --dir out --pol none -j MASQUERADE iptables -t nat -I POSTROUTING -s "$L2TP_NET" -o "$NET_IFACE" -j MASQUERADE echo "# Modified by hwdsl2 VPN script" > "$IPT_FILE" iptables -A FORWARD -j DROP iptables-save >> "$IPT_FILE" fi bigecho "Enabling services on boot..." systemctl --now mask firewalld 2>/dev/null systemctl enable iptables fail2ban 2>/dev/null if ! grep -qs "hwdsl2 VPN script" /etc/rc.local; then if [ -f /etc/rc.local ]; then conf_bk "/etc/rc.local" else echo '#!/bin/sh' > /etc/rc.local fi cat >> /etc/rc.local <<'EOF' # Added by hwdsl2 VPN script (sleep 15 service ipsec restart service xl2tpd restart echo 1 > /proc/sys/net/ipv4/ip_forward)& EOF fi bigecho "Starting services..." restorecon /etc/ipsec.d/*db 2>/dev/null restorecon /usr/local/sbin -Rv 2>/dev/null restorecon /usr/local/libexec/ipsec -Rv 2>/dev/null sysctl -e -q -p chmod +x /etc/rc.local chmod 600 /etc/ipsec.secrets* /etc/ppp/chap-secrets* /etc/ipsec.d/passwd* iptables-restore < "$IPT_FILE" # Fix xl2tpd if l2tp_ppp is unavailable if ! modprobe -q l2tp_ppp; then sed -i '/^ExecStartPre=\//s/=/=-/' /usr/lib/systemd/system/xl2tpd.service systemctl daemon-reload fi mkdir -p /run/pluto service fail2ban restart 2>/dev/null service ipsec restart 2>/dev/null service xl2tpd restart 2>/dev/null swan_ver_url="https://dl.ls20.com/v1/amzn/2/swanver?arch=$os_arch&ver=$SWAN_VER" swan_ver_latest=$(wget -t 3 -T 15 -qO- "$swan_ver_url") if printf '%s' "$swan_ver_latest" | grep -Eq '^([3-9]|[1-9][0-9])\.([0-9]|[1-9][0-9])$' \ && [ "$SWAN_VER" != "$swan_ver_latest" ] \ && printf '%s\n%s' "$SWAN_VER" "$swan_ver_latest" | sort -C -V; then cat <